If everyone only submits one application for trademark registration (complete information), then the person who finally gets the certificate must submit the application earlier.
Then infer from what you said above:
Guess 1: You should have registered successfully, so he has a so-called transfer request.
Guess 2: He has been using the name of this trademark, but it is not registered. He can indeed apply for cancellation during the examination of trademark registration. It depends on whether the other party's legitimate reasons are sufficient, but it is possible that your registration is unsuccessful. )
According to speculation 2, in the same way, if he successfully cancels the trademark you want to register, you can also apply for cancellation of his registration during the registration of this trademark. The information you need to prepare is whether you have the use certificate of this trademark.
Suppose the brand name is "Baidu".
As long as you prove that you used this name earlier than him, you can basically apply for cancellation of his application.